Film strip feeding mechanism



NOV. 10, J J. FILM STRIP FEEDING MECHANISM Filed April 30, 1962 United States Patent 3,156,400 FILM STRIP FEEDING MECHANISM John Joseph Rigby, Kelston, London Road, Camberiey, Surrey, England Filed Apr. 30, 1962, Ser. No. 191,370 Claims priority, application Great Britain May 3, 1961 7 Claims. (Cl. 226-157) This invention relates to film projection apparatus and is concerned with an improved film strip feeding mechamsm.

In film projection apparatus in which the feeding of the film is manually operated, as distinct from kinematographic apparatus in which the feed mechanism is automatic and timed to coincide with the closing and opening of a shutter, one of the problems has been to find a simple but accurate form of drive by which the film will be advanced one frame at a time.

According to the present invention film strip or slide feeding mechanism comprises a solenoid by which a ratchet or claw member carried by a plunger under the a movement of the plunger, release of a push-button type make and break switch in the solenoid circuit will release the plunger and allow the latter and its claw member to return to its initial or inoperative position.

Provision may be made for reversal of the film strip feed by duplicating the solenoid and ratchet and plunger mechanism.

In one construction in accordance with the invention, the drive spindle, by which drive is transmitted through sprockets thereon engaging the film, is provided with two discs connected to one another by a series of circumferentially spaced pins for co-operation with a lever arm or rod pivotally attached at one end to the plunger of the solenoid, the other end of the lever arm or rod being connected to a return spring.

A ratchet claw is formed on one side of the lever arm for engagement with the pins, of which conveniently there may be four so that the spindle is rotated through 90 each time the solenoid is excited.

The invention is illustrated in the accompanying drawings in which FIGURE 1 is a sectional elevation of a film strip feed including the spool housings fitted with the strip feeding mechanism of this invention,

FIGURES 2 and 3 are vertical sections respectively on the lines IIII and IIIIII of FIGURE 1.

In the drawings B indicates a base plate, in which is an aperture A through which the film strip or a slide to be viewed is illuminated. C is a standard type of clamp plate which is attached to the plate B by a hinge H and is releasably held by a catch D to facilitate insertion of the film strip. G, indicates plate glass screens, fixed re spectively to the base plate B and clamp plate C.

S1 and S2 indicate the spool housings into and from which a length of the film strip is wound.

Extending along one side of the plate B is a flange 1 fitted with a detachable cover plate 2 providing an interior housing 3 for the strip or slide feeding mechanism of the present invention. This mechanism consists of two solenoids, the coils of which are indicated respectively at 4, 5, the core of each solenoid being formed by soft iron plungers 6, 6'.

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Each plunger 6, 6' is pivotally connected to one end of a connecting rod 8 formed at its other end with a ratchet element or claw 9 for successive engagement with each one or other of a series of circumferentially spaced drive pins 10 secured between discs 12, 12. The discs 12, 12' are mounted on one end of a drive spindle 13, whose other end has a control knob 14 by which it can be turned by hand.

A drum 15 having a spaced series of sprocket teeth 16 provides the necessary drive for advancing the film past the gate A. Cooperating with the drum 15 are retaining rollers 15'. The spindle 13, which is journalled to rotate in a bushing 17 in the flange wall 1, is normally maintained in driving engagment with the discs 12, 12' through a clutch device including a plate 18, this plate, together with the discs 12, 12, being faced with hardened pads 20 which are pressed against one another by means of a clutch spring 21. This device operates as a slipping clutch so that the spindle 13 can be turned by hand for small adjustments such as in registering the film with the frame line.

As can be seen from FIGURE 3, four pins 19 are provided so that a single displacement of the selected rod 5 against the action of a return or biasing spring 26 when its associated solenoid 4 or 5 is excited will cause the discs to revolve and move through a quarter turn i.e.

To prevent unrestricted movement of the discs there is provided a spring pressed plunger 22, the spherical end 23 of which in the rest position enters one of four notches 24 in the perimeter of the disc 12'.

FIGURE 3 shows the feed mechanism in the operative position following operation of the left-hand solenoid 4, and 6, when the plunger 6, together with the rod 8, has just been displaced in the direction of arrow X thus imparting a clockwise rotation to the discs 12, 12' and to the spindle 13. In order to provide clearance for the movement of the next pin, indicated at 10', the end of the claw member is out way as indicated at 25 and similarly there 'is provided a corresponding cut-out 25 in the member rod 8. As shown in FIGURE 3, the position and depth of the cut-out part or depression 25 are such that the pin 10' following the actuated pin 10 may move sufiiciently to permit a predetermined step of rotation of the drive member 12-17-1640 and to arrest rotation of the drive member after this step of rotation. The depression 25' acts similarly. The hinge connection of the connecting rod 8 to the plunger 6 enables the rod 8 to swing and the ratchet element 9 to move relatively away from the drive member when the connecting rod is returned to its lower or inoperative position by the biasing spring 26.

Clearly when the right-hand solenoid 5, 6' is excited, rotation of the discs 12, 12 and thus of the spindle 13 will be anticlockwise.

The solenoids may be connected in an electric circuit as shown by the dotted lines in which is a two-way switch diagrammatically shown at 30 for closing the circuit through one or other of the solenoids 4, 5.

The film drive of this invention has the advantage or simplicity and further, not only is the motion a positive one, but it ensures accuracy of movement, sincethe film will be shifted a distance equal to one frame, each time the drive is operated and the accuracy of the movement is further ensured by the second groove in the member rod engaging the next pin 10.

That action of 10' in engaging with 25 looks mechanism in order to turn racking lever 14 to frame film.

What is claimed is:

1. In a strip feeding mechanism, a base; a drive spindle rotatably supported on said base; a sprocket drum fixed to said drive spindle for moving said strip; and solenoid actuated drive means for imparting a step-by-step rotational movement to said spindle and said sprocket drum to move said strip step-by-step, said drive means comprising a drive member mounted on said drive spindle, a series of circumferentially spaced drive pins carried by said drive member, a connecting rod formed with a ratchet element and being movable to an operative position for causing engagement of said ratchet element with said drive pins individually, a solenoid the plunger of which is hingedly connected to the other end of said connecting rod, whereby said connecting rod may swing to enable said ratchet element to move relatively away from said drive member when said connecting rod is moved from its operative position to an inoperative position, spring means for biasing said ratchet element into its inoperative position, and switch means for energising said solenoid to move said connecting rod to its operative position thereby to move said drive member through a predetermined angle of rotationv 2. A mechanism as claimed in claim 1 in which the drive member comprises two axially spaced discs fast on the spindle and the drive pins are secured between said discs.

3. A mechanism as claimed in claim 1, including a second solenoid and a second connecting rod and ratchet element associated therewith for turning said drive spindle through a predetermined angle of rotation which is opposite to that effected by the first mentioned connecting rod and ratchet element.

4. A mechanism as claimed in claim 2, including a spring actuated plunger and in which at least one of said axially spaced discs is formed with circumferentially spaced notches, said notches co-operating with said spring actuated plunger for preventing unrestricted movement of said discs.

5. A mechanism as claimed in claim 4, including a clutch interposed between said axially spaced discs and said drive spindle, and manually operated means for turning said drive spindle without turning said axially spaced discs as permitted by slipping of said clutch.

6. A mechanism as claimed in claim 1 in which said connecting rod is formed with a depression adjacent said ratchet element and being positioned relatively to the latter and of such depth as to receive the one of said drive pins which follows the drive pin engaged by said ratchet element, whereby to permit said predetermined angle of rotation of said drive member and to arrest rotation of the drive member at the end of said angle of rotation.

7. In a strip feeding mechanism, a base; a drive spindle rotatably supported on said base; a drum connected to said drive spindle and being rotatable therewith for moving said strip; and solenoid actuated drive means for imparting a step-by-step rotational movement to said drive spindle and drum to move said strip step-by-step, said drive means comprising a drive member drivingly connectcd to said drive spindle, a series of circumferentially spaced drive pins carried by said drive member, a connecting rod having a ratchet element and being movable to an operative position for causing engagement of said ratchet element with said drive pins individually, a solenoid having a plunger connected to said connecting rod, means for biasing said connecting rod into an inoperative position, and switch means for energising said solenoid to move said connecting rod to its operative position thereby to move said drive member through a predetermined angle of rotation, said connecting rod being formed with a depression adjacent said ratchet element and being positioned relatively to the latter and of such depth as to receive the one of said drive pins which follows the drive pin engaged by said ratchet element, whereby to permit said predetermined angle of rotation of said drive member and to arrest rotation of the drive member at the end of said angle of rotation.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A STRIP FEEDING MECHANISM, A BASE; A DRIVE SPINDLE ROTATABLY SUPPORTED ON SAID BASE; A SPROCKET DRUM FIXED TO SAID DRIVE SPINDLE FOR MOVING SAID STRIP; AND SOLENOID ACTUAATED DRIVE MEANS FOR IMPARTING A STEP-BY-STEP ROTATIONAL MOVEMENT TO SAID SPINDLE AND SAID SPROCKET DRUM TO MOVE SAID STRIP STEP-BY-STEP, SAID DRIVE MEANS COMPRISING A DRIVE MEMBER MOUNTED ON SAID DRIVE SPINDLE, A SERIES OF CIRCUMFERENTIALLY SPACED DRIVE PINS CARRIED BY SAID DRIVE MEMBER, A CONNECTING ROD FORMED WITH A RATCHET ELEMENT AND BEING MOVABLE TO AN OPERATIVE POSITION FOR CAUSING ENGAGEMENT OF SAID RATCHET ELEMENT WITH SAID DRIVE PINS INDIVIDUALLY, A SOLENOID THE PLUNGER OF WHICH IS HINGEDLY CONNECTED TO THE OTHER END OF SAID CONNECTING ROD, WHEREBY SAID CONNECTING ROD MAY SWING TO ENABLE SAID RATCHET ELEMENT TO MOVE RELATIVELY AWAY FROM SAID DRIVE MEMBER WHEN SAID CONNECTING ROD IS MOVED FROM ITS OPERATIVE POSITION TO AN INOPERATIVE POSITION, SPRING MEANS FOR BIASING SAID RATCHET ELEMENT INTO ITS INOPERATIVE POSITION, AND SWITCH MEANS FOR ENERGISING SAID SOLENOID TO MOVE SAID CONNECTING ROD TO ITS OPERATIVE POSITION THEREBY TO MOVE SAID DRIVE MEMBER THROUGH A PREDETERMINED ANGLE OF ROTATION. 